DNA and Protein Synthesis Flashcards
Why is DNA universal?
The genetic code is the same in all living organisms
What does GGT code for?
Glycine
Why is DNA Non-Overlapping?
Each DNA triplet and gene is separate
Why is DNA degenerate?
The same amino acid can be coded for by more than one triplet
How does DNA become pre-mRNA?
It is transcribed
How does pre-mRNA become mRNA?
It is spliced
How does mRNA become proteins?
it is translated
How is genetic information stored in eukaryotes?
- Long, linear double helix- Found in nucleus- Folded around histones- Folded into chromosomes - Containing introns and exons
How is genetic information stored in prokaryotes?
- Short circular loop of DNA- No histones- No nucleus- Have plasmids- No introns
What is a gene?
A sequence of DNA that codes for a polypeptide, protein or functional RNA
What is the locus?
The position of a gene on a chromosome, the location of the specific gene will remain the same in all organisms of the same species
What is a DNA triplet?
A sequence of 3 DNA bases that code for a specific amino acid
What were mitochondria and chloroplasts initially?
Free living therefore they contain their own DNA, they can synthesise enzymes needed for their functions
What are introns?
Non coding multiple repeats that are found in pre-mRNA and do not code for polypeptides
How is transcription carried out? (before splicing)
- DNA helicase separates out DNA strands by breaking hydrogen bonds- Free RNA nucleotides attach to the template strand by complimentary base pairing- RNA polymerase joins RNA nucleotides together with phosphodiester bonds formed by condensation reactions- H-bonds reform- premRNA is formed in eukaryotes- mRNA is formed in prokaryotes
What is splicing?
Removal of introns (non coding sections)
Which organisms do not undergo splicing
Prokaryotes
How does splicing happen?
premRNA (introns and exons) undergoes splicing to remove the non coding sections (introns) to leave just the coding sections (exons) and mRNA is formed
What happens after splicing?
mRNA leaves the nucleus and undergoes translation in the cytoplasm
What is a codon?
A triplet of bases found on mRNA that codes for a specific amino acid
What is an anticodon?
A triplet of bases found of tRNA that is complimentary to the mRNA codon
What is tRNA?
Transfer RNA, a polypeptide folded by H-bonds with an amino acid attached. The amino acid is specific to the anticodon
How does translation take place?
- A ribosome binds onto mRNA at the start of the start codon- Codon on the mRNA is matched to the complimentary anticodon on tRNA by complimentary base pairing - Ribosome hold the complimentary tRNA in place whilst the amino acids are joined together by a peptide bond- Used tRNA returns to the cytoplasm to attach to a new amino acid (complimentary to its anticodon) this uses ATP
Where does the ribosome attach and detach?
The start and stop codons
What is formed from translation?
A polypeptide chain
After a mutation, what changes within the DNA?
The sequence of bases
Within a bacterial cell, around which protein does the DNA wind?
Not wound as it is prokaryotic
What do we call a sequence of three bases within a DNA strand?
Triplet
What do we call a sequence of three bases on a mRNA strand?
Codon
What do we call a sequence of three bases on a tRNA strand
Anticodon
What can a pair of matching chromosomes be defined as?
Homogenous pair
What type of cells are plant cells?
Eukaryotic
What can the locus of a gene be defined as?
The position of a gene on a chromosome
Within a plant which organelle stores genetic information?
Nucleus
What is the different form of a gene known as?
An allele
What is the base sequence of DNA having a change occur known as?
A mutation
How could a non-functional enzyme come about?
High temperatures, change in pH or a mutation of the gene that coded for the protein
Where, within a cell, are proteins produced?
Ribosomes
A human sperm cell contains how many chromosomes?
23
Within our body cells, we have a total of how many chromosomes?
46
Where is human DNA stored?
Chromosomes
One amino acid is coded for by how many bases?
3
In which organelle does transcription happen?
Nucleus
RNA is made of how many strands?
1
Two amino acids are held together by which type of bond?
Peptide
Which base is not in an RNA strand?
Thymine
In which organelle does protein synthesis occur?
Ribosome
DNA is transcribed into what type of RNA?
pre-mRNA / mRNA
Amino acids are joined together by which type of reaction during protein synthesis?
Condensation
Within protein synthesis, where does translation take place?
Ribosome
What type of sugar forms part of an RNA molecule?
Ribose
What does the DNA antisense strand act as?
The template strand for mRNA
What is the DNA antisense strand complimentary to?
The DNA sense strand
What does the DNA sense strand not act as?
The template strand for mRNA
What does pre-mRNA contain that need to be removed?
Introns
How are introns removed?
pre-mRNA is spliced to remove introns and leave the coding exons (eukaryotes only)
